Refrigeration



Aug. 23, 1932. ILLIA S 1,873,519

REFRIGERATION Filed 0ct.-7, 1930 1 IQ 2 4 W166i j 15 11 INVEN'TOR Edward T Williams- BY Patented. Aug. 23, 1932 Application filed October], 1930.: sr1a1-No. 1s6,s29.

I This invention relates to refrigerating ap-- tinuation in,

paratus of the compressor:condenser-expander type, and more particularly to a. meansfor returning lubricant from the [Qevaporator to-the compressor in a flooded evaporator'type system. H I V Dueto the relatively low volatllenature of lubricants as compared to refrigerants,

quantities of the former which are used to,

10 lubricate the compressorand are carried with the refrigerant to the evaporator remain therein and gradually accumulate 111'lt1l the efficiency of the system is seriously impalred. It is, therefore, necessary to provide some 5 means for'returning the lubricantfrom the:

evaporator to the compressor. .An effective method of accomplishing this is to introduce the lubricantfrom theevaporator lnto the vapor suction line where it is drawn along pressor. a a

This invention contemplates ameans util zing the boiling action of the refrigerant when it evaporates to effect the transferof the lubricant into the vapor suction line where 1t can be drawn back into the compressor. A very satisfactory way to do this 1s by providing in the evaporator an inverted vessel enclosing an upwardly converging chamber 1' 1g. 1 with which is open at the bottom below the normal with the refrigerant vapor back to the comliquid level in the evaporator and communi eating at the top withvthe vapor suction line to the compressor. Bubbles resulting from the evaporation of the liquid refrigerant in the evaporator carry lubricant which may be floating on the surface of or mixed'with the liquid refrigerant in the evaporator and due to the gradual reduction in area of the cross section of the upwardly converging chamber from the bottom thereof to the normal level of the liquid therein, there is an increased agitation and a distinct foaming at the surface of the fluid under the inverted vessel ried to the top ofthechamber where they are drawn off throughthe vapor suction line; This is more fully set forth in my co-pending application Serial Number 356,338, filed April 19, 1929, of which this case is aconwhich results in lubricant bubbles. being car tend refrigerant stood byreference to the following tlon taken in connection with the accompany an inverted vessel 16 part. The present inventioncon tem latestheprovision of means whereby" eat of the incoming liquid refrigerant is utilized to increase the amount ofebulli- ;tion .of the liquid W'ithill'. the upwardly con verging chamber under, the inverted vessel thereby 'increasing'fthe effectiveness of this method of lubricant return. This is'of conslderable importancewhen It is necessary or desirable to limit the size of the inverted vesv .sel, as, for instancewhen th e evaporator is of such small size or of such design that 1t1s not adapted toreceive an inverted vessel of sufficient size to allow the necessary decrease mcross sectional area from the bottom thereof to the liquid level therein to causel the rising vaporto gain such a velocity that there is created the requisite foaming at the surface.

This invention will be more readily underdescriping drawingin which like reference characters indicate like parts. 1

In the drawing: Fig. 1 is a vertical section of an evaporator of the flooded type. inwhich is provided a lubricant returnmeans, contemplated by this invention; i Fig. 2 a plan view. of the evaporator in part of the outer casing broken awayiand, Y a V Fig. 3 a plan view of a slightly modified arrangement of the parts shown in Fig. .1".

eferring to Figures 1 and 2, an evaporator 85 of the flooded type of any desired construction comprises a casing 10 with a portion 11 threaded at 12 or otherwise adapted to re-- ceive a closing member'l3 through which exinlet conduit 14 and vapor WVithin the evaporator is enclosing an upwardly converging chamber 17 which is open at the bottom below the normalliquid level-in the evaporatorand communicates at its upper portion with vapor suction line 15 through conduitlS. An opening 19 in the vapor suction line 15 communicates with the vapor space abov'e 'the normal liquid level in the suction line 15.

evaporator to allow rofrigerantkvapor to ben V returned tothe compressor. i

Evaporation or boiling'of the liquid refrigerant in the evaporator causes bubbles of refrigerant vapor to rise vertically through the accumulation of refrigerant and lubriface within the chamber. The velocity of' the upwardly rising vapor bubbles increases- -ant vapor.f

cant.

I Due to the constantly decreasing cross'sectional area of the chamber 17 from the bot-i tom thereof to the'su rface of the liquid therein an excessive foaming is producedat said surface due to the velocity of the upwardly rising bubbles when'they re'ach "th liqultl sur f in'the same ratio that the cross sectional area decreases. For instance,tlie inverted vessel 16 may besubstantially cone shaped as shown with-thecross sectional area of chamber 17 at the liquid surface of the cross sect-ional meant the open bottom of thevessel: The

velocity of the vapor-bubbles' mo'ving upwardly from. the" open bottom of 'the vessel will'have increased ffour fold'when they reach the-surface of theliquid. Due to the surface tension of lubricant which is mixed with the refrigerant or floating on the surface thereof each of the rapidly-rising vapor bubbles:takes on a thin film of the lubricant and (lueyto the increased velocity, as explainedabove, a violent foaming occurs at the's-ur- "face. of the liquid. The foam comprises a myriad-0f small 'bubbleseach'composed of a lubricant film envelope filled with'refriger- NYhenthe lubricant is broken up into a great number of minute' films the specificgravity-of the-massof lubricantthus broken up is greatlyrreduced. 1 Due to this man tion in the specific gravity of the lubricant and the difference in pressure between'the vapor suction line and the upwardly converging chamber, and also due to the velocity with which they leave the surface of the liq- 'uid, the bubbles are carried to the top of chamber 17 where thelubricant and refrigerant vapor are drawn offth-rough eonduit18 and the vapor suction line 15 and returned to thecompressor;

- f Liquid're-frigerant is supplied to the evaporator throughi'conduit 20 which may be in the-form of a capillary tube as -shown -forregulating the supqily to the evaporator to maintainthe liquid'leveltherein substantial-'- ly constant." To give conduit 20 sufiicient length it may be coiled at '21 before discharg-' inginto the evaporator at 14.

-If the cone shaped-or upwardly tapering" member-16 is not ofs'uflicient size, that is,-'if thedecrease in c-ros'ssectional area from the bottom thereof to the normal liquid level in the evaporator in not great enough, there will not be sufficient .foamingof the liquid refrig erant inchamber 17 under certain operating conditions, to=carry the lubricant to the top." To createsufiicient ebullition of the liquid, refrigerant in chamber 17 in such instance,

' the evaporator,

the refrigerant inlet conduit 20 is positioned adjacent to or within the vapor suction line 15, and extended into theevaporator where it is welded to or otherwise placed in good thermal conductive relation with the inverted vessel 16 as at 22. Conduit 2Q isthen given a numberofturns" either on there is a falling temperature gradientfrom the source of supply to the discharge point in the evaporator anditis desirable to obtain asmuch heat as possible from the incoming der the inverted ve ssel.

liquid refrigerant for heating the liquid 1111 11 With this construction the liquid refriger: 7

ant conduit is in goodjthermal relation withff I I 'both'the vapor suction lineand the inverted vess el '-16, and the heat of the *lncon'nng liquid;

refrigerant is utilized to produce greater evaporation of the refrigerant inlchamber l'i', and also to vaporize any liquid refrigerant which maybe carried over into the vapor suction line.

It is,"of course,notnecessary to use a capillary'; tube for -'controll ing the liquid refriger'ant delivered to the=evaporat=or but any well'known means such as a float valvem'ay' be substituted, in which case the liquid rewouldbe extended into thermal exchange re- 'lation to the liquid'in the upwardly convergj ing chamber.

that'va'riou's other changesmay be made in 1 10b [frigerant conduit 20' would be connected'to an inlet val-ye'and the outlet from such valve the- "construction and arrangement without departing from thespirit ofthe invention and therefore the invention is not limited to what is shown in'th e drawing and described" v a inthe specification but'only as indicated in. the appended claims."

L The method ofcirculating lubricant in cu a refrigerating system which comprises'applying'the' -specific heat ofcon'densed refriger'- 7 ant to a'nrya evin said bodyQConst ricting the upward path'of flow of a vapor bubbles in said bbilfa body of liquidrefrigerantwith lubricant therein to form bubbles of refrigerbodytdfoam the lubricant and removing the lubricant foam from" the presence of said 2. The method of circulating lubricant in a refrigerating system which-comprises .ap-

plying the specific heat of condensgrrefrigera ant to boil abody of liquid refrigerant with lubricant therein to form bubblesof refrigerant vapor in said body and gradually con- 7. e v It will beobvious to those skilled in the art &

chamber, and a refrigerant supply line extending into said evaporator in thermal conrluctire relation with said invertetl vessel.

in estiinony whereof I. alfix my signature.

EDWARD T. WILLIAMS.

comprises maintaining an'appreciable quantity of liquid refrigerant and some lubricant in the evaporator, applying the specific heat of liquid refrigerant from the condenser to hoil liquid refrigerant in the evaporator, con strioting the upward passage of vapor bubbles in the boiling refrigerant to produce a lubricant foam, removing the foam from the evaporator and delivering said; foam to the compressor.

4. In a refrigerating system of the (one pressor-condenser-expander type, means for returning lubricant from the evaporator to the compressor comprising an inverted vessel enclosing an upwardly converging chamber open at the bottom below the normal liquid level in the evaporator and communicating at the top with the vapor suction line, an evaporator refrigerant inlet conduit in thermal conductive relation with said inverted vessel. l

5. In a refrigerating system, an evaporator adapted to contain a quantity of liquid refrigerant and lubricant, means for inaintaining a substantially constant liquid level within said evaporator, an inverted vessel within said evaporator, said vessel having an upwardly converging chamber therein open at the bottom below the normal liquid level in said evaporator and communicating at the top with a vapor suction line anrl means for applying the specific heat of the incoming liquid refrigerant to said inverted vessel.

6. In a refrigerating system, an evaporator including a header, a supply of liquicl refrigerant for said evaporator, means for 'zmiinraining the liquid level in said header sub tantially constant, an inverted vessel Within sairl header, said vessel having an up wartlly converging chamber open at the loottom below the normal liquid level in said header and communicating at the top with a vapor suction line and means for applying the specific heat of said refrigerant supply to said inverted vessel.

T. In a refrigerating system of the com pressoncondenser-expander type, in combination, an evaporator, means for maintain ing a substantially constant fiuitl level in Silill evaporator, an inverted vessel within said evaporator, said vessel having an upwardly converging chamber open at the hottornhelow the normal liquid level in the evaporator, a vapor suction line extending into said evaporator and connnunicating With the vapor space in said evaporator and thetop of said Ill) 

